Many modern vehicles, such as aircraft, are equipped with a wide variety of electrical and computing systems that monitor and, in some instances, control various operational aspects of the aircraft. One of the tasks often performed by these systems is to gather information from various instruments, such as a compass and an altimeter, and display the information on single display device, such as a primary flight display (PFD).
PFDs are also often used to display, typically in a perspective view, the terrain over which the aircraft is flying, including the locations of various landmarks, such as landing strips. When combined with recent advances in satellite imaging and Global Position Systems (GPS), it is possible for modern computer systems to display the terrain on the PFD with a relatively high level of detail, including three-dimensional contouring. Situations arise in which the pilot, or other user, is trying to navigate the aircraft by viewing only the PFD (e.g., in severe weather or in a vehicle without windows). In such situations, the movement, spacing, and size of the features shown on the digital terrain assist the pilot by providing an indication of the altitude and speed of the aircraft.
In order to generate the images of the terrain, aircraft often utilize onboard databases that include terrain elevation data, such as Digital Elevation Model (DEM) data, in combination with other components, such as Global Positioning System (GPS) receivers. However, due to performance limitations of the processors that are used to generate the digital terrains, often not all of the available terrain elevation data is used. That is, in order to save system resources, the digital terrain is shown at a resolution lower than that of the terrain elevation data. This reduction in resolution is often performed by sampling the terrain elevation data and results in the terrain being shown less accurately than possible.
To ensure the accuracy with which the terrain is shown to the pilot, the terrain elevation data may be checked to ensure that none of the unselected data points have elevations that are higher than nearby selected data points. If unselected data points are found to be higher than nearby selected data, the elevation of the selected data is increased to that of the unselected data. Such a method results in such a conservative image of the terrain that down range features are often erroneously obscured from view on the PFD.
Accordingly, it is desirable to provide a method and system for displaying a digital terrain that more accurately represents the actual terrain while still only utilizing a portion of the possible terrain elevation data resolution. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.